Root canals are prepared endodontically by removing the nerve and pulp for subsequent obturation with an appropriate obturator. Before the obturation step, the root canal must be disinfected to reduce the risk of post treatment infection.
WO 00/74587 discloses a device for photosynthesizing a root canal. In use, the endodontically prepared canal is filled with a photosynthesizer solution such as toluidine blue dye in an aqueous solution. On contact with the bacteria, the dye or other photosynthesizer conjugates with the bacteria. Next, a conventional root canal file that is mounted on a dental hand piece is placed in the photosynthesizer solution filled root canal and the file is rotated in the root canal so as to distribute the photosynthesizer solution throughout the root canal. The photosynthesizer solution is absorbed by bacteria in the root canal and releases O− (singlet oxygen) when exposed to light with a given wavelength which is specific to the absorption of each photosynthesizer. O− is highly poisonous for bacteria. Thereafter, an optical fiber with a special spherical tip is placed in the root canal. The optical fiber does not have a reflective layer along its length. The size of the spherical tip is such that the optical fiber can enter about ⅔ of the length of the root canal, i.e. the tip of the optical fiber cannot reach the apex of the root canal. The optical fiber is connected to a laser unit containing a conventional laser. The light generated by the laser is thus applied to the interior of the root canal to photoactivate the photosynthesizer solution. Thus, the photosynthesizer solution releases O− resulting in the death of the bacteria in the root canal. Thereafter the root canal is dried and the actual obturation process begins.
There are several disadvantages associated with this known device. The process requires the use of a handset and file as well as the laser unit with the optical tip. The dental practitioner needs to swap devices during the procedure thereby complicating and prolonging the procedure. This known method uses a relatively expensive and sensitive laser unit. Further, the spherical optical tip cannot reach down to the apex of the root canal and thus the efficiency of the light exposure of the apex and the portion of the root canal near the apex cannot be guaranteed. Also, the size of the spherical tip has to match the size of the endodontically prepared root canal. The size of the root canal depends on the anatomy of the tooth concerned and the size and shape of the root canals that have been used to prepare the canal. Consequently, the dental practitioner needs to have a variety of different sized light guides in stock, thereby increasing costs and complexity of the disinfection procedure.
Caries affected teeth are prepared by excavating bacteria infested dentine material. Conventionally the excavation is performed very thoroughly to ensure that the remaining dentine material is not infected. Thus, the excavation is often performed more extensively than strictly required from a “constructional” point of view due to the risk of subsequent infection.